Difference between revisions of "Serial port"

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= RS232-USB Converters =
= USB to Serial Converters =
To operate devices having RS-232 interfaces on computers that have only USB interfaces available, RS232 to USB converters are available. Many different chipsets exist that have slightly different properties, often supporting only a subset of what common UARTs like the 8250/16550A can do. Please note that a driver for the respective operating system is required (sometimes included in the OS already, e.g. mostly for Linux).
To operate devices that have RS-232 or TTL serial interfaces on computers that have only USB interfaces, converters are available. Many different chipsets exist that have slightly different properties, often supporting only a subset of what common UARTs like the 8250/16550A can do. Please note that a driver for the respective operating system is required (sometimes included in the OS already, e.g. mostly for Linux).
Many original USB cables from manufacturers use these converters, too, either with the chip manufacturer's or a custom USB ID.


Some RS232 devices won't work on RS232-USB converters because they expect a higher signal voltage, e.g. to drive optocouplers.
Some RS232 devices won't work on RS232-USB converters because they need a higher RS232 signal voltage than supplied by most of these converters, e.g. to drive optocouplers in the interface.


Common chipsets are:
Common chipsets are:
Line 16: Line 17:
! Manufacturer
! Manufacturer
! Type
! Type
! OS
! USB
! Data Bits
! Data Bits
! Non-standard baud rates
! Non-standard baud rates
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|-
|-
| Prolific
| FTDI
| PL-2302x
|
|
|  
|  
|  
| 7,8
|  
|  
|  
|  
| [http://www.prolific.com.tw/US/ShowProduct.aspx?pcid=41&showlevel=0017-0037-0041 1]
|  
|  


|-
|-
| Prolific Fake
| rowspan="8" | MOSChip (Asix)
| (PL-2302)
| MCS7703
| 1.1
|
|  
|  
|  
|  
|  [http://www.asix.com.tw/products.php?op=ProductList&PLine=74&PSeries=109 1]
| 1 serial port; out of production
|-
| MCS7710
| 1.1
|  
|  
|  
|  
|  
|  
| It seems that fakes of prolific chips with limited reliability exist.[http://www.prolific.com.tw/US/ShowProduct.aspx?p_id=155&pcid=41 1]
| [http://www.asix.com.tw/products.php?op=ProductList&PLine=74&PSeries=109 1]
| 1 serial port; out of production


|-
|-
| FTDI
| MCS7815
| 1.1
|
|
|  
|  
| [http://www.asix.com.tw/products.php?op=ProductList&PLine=74&PSeries=109 1]
| 1 serial, 1 parallel port
|-
| MCS7717
| 1.1
|  
|  
|  
|  
|  
|  
|  [http://www.asix.com.tw/products.php?op=ProductList&PLine=74&PSeries=109 1]
| 1 serial, 1 parallel port and 3-port USB hub; out of production
|-
| MCS7720
| 1.1
|  
|  
|  
|  
|  
|  
|  [http://www.asix.com.tw/products.php?op=ProductList&PLine=74&PSeries=109 1]
| 2 serial ports


|-
|-
| rowspan="3" | MOSChip (Asix)
| MCS7810
| MCS7810
|  
| 2.0
|  
|  
|  
|  
|  
|  
|  [http://www.asix.com.tw/products.php?op=ProductList&PLine=74&PSeries=109 1]
|  [http://www.asix.com.tw/products.php?op=ProductList&PLine=74&PSeries=109 1]
| 1 RS232 port
| 1 serial port


|-
|-
| MCS7820
| MCS7820
|  
| 2.0
|  
|  
|  
|  
|  
|  
| [http://www.asix.com.tw/products.php?op=ProductList&PLine=74&PSeries=109 1]
| [http://www.asix.com.tw/products.php?op=ProductList&PLine=74&PSeries=109 1]
| 2 RS232 ports
| 2 serial ports


|-
|-
| MCS7840
| MCS7840
|  
| 2.0
| 5-8
| 5-8
| yes; broken on Mac
| yes; broken on Mac
|  
|  
|  [http://www.asix.com.tw/products.php?op=ProductList&PLine=74&PSeries=109 1]
|  [http://www.asix.com.tw/products.php?op=ProductList&PLine=74&PSeries=109 1]
| 4 RS232 ports  
| 4 serial ports  
|-
| Prolific
| PL-2302x
|
| 7,8
|
|
| [http://www.prolific.com.tw/US/ShowProduct.aspx?pcid=41&showlevel=0017-0037-0041 1]
|
 
|-
| Prolific Fake
| (PL-2302)
|
|
|
|
|
| It seems that fakes of prolific chips with limited reliability exist.[http://www.prolific.com.tw/US/ShowProduct.aspx?p_id=155&pcid=41 1]
 
|-
| SiLabs
| CP2102
|
| 5,6,7,8
|
|
|
|


|}
|}

Revision as of 23:36, 21 November 2013


Serial Ports are a common way to communicate with devices. The most common serial ports, as used by devices like Metex/Voltcraft multimeters, are RS-232 interfaces.


USB to Serial Converters

To operate devices that have RS-232 or TTL serial interfaces on computers that have only USB interfaces, converters are available. Many different chipsets exist that have slightly different properties, often supporting only a subset of what common UARTs like the 8250/16550A can do. Please note that a driver for the respective operating system is required (sometimes included in the OS already, e.g. mostly for Linux). Many original USB cables from manufacturers use these converters, too, either with the chip manufacturer's or a custom USB ID.

Some RS232 devices won't work on RS232-USB converters because they need a higher RS232 signal voltage than supplied by most of these converters, e.g. to drive optocouplers in the interface.

Common chipsets are:

Manufacturer Type USB Data Bits Non-standard baud rates Max. baud rate Homepage Remarks
FTDI


 MOSChip (Asix) MCS7703 1.1 1 1 serial port; out of production
MCS7710 1.1 1 1 serial port; out of production
MCS7815 1.1 1 1 serial, 1 parallel port
MCS7717 1.1 1 1 serial, 1 parallel port and 3-port USB hub; out of production
MCS7720 1.1 1 2 serial ports
MCS7810 2.0 1 1 serial port
MCS7820 2.0 1 2 serial ports
MCS7840 2.0 5-8 yes; broken on Mac 1 4 serial ports
Prolific PL-2302x 7,8 1
Prolific Fake (PL-2302) It seems that fakes of prolific chips with limited reliability exist.1
SiLabs CP2102 5,6,7,8
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